For the production of open-end spinning rotors, a multitude of different methods have become known. Spinning rotors are frequently made by turning, and are provided with a coating to make them more resistant to the abrasive action of fibers. In order to be able to resume the spinning procedure after an interruption of the spinning process, for example, through a thread break or a quality cut, it is necessary to, in a defined manner, cut to length the yarn end to be pieced, and to prepare it for piecing. Moreover, for preparing a yarn end, various methods have become known. For example, it is customary to fray the yarn end by means of an air flow.
DE 10 2012 110 926 A1 describes a method for preparing a yarn end for piecing in, with which the yarn is not prepared for piecing by a separate preparation device outside the spinning device, but is prepared within the spinning device through the rim of the spinning rotor. For this purpose, the yarn is sucked into the vacuum channel via a draw-off tube and a draw-off nozzle, through which the open-end spinning device is supplied with negative pressure, and is held therein. In this case, the yarn runs over the open rim of the spinning rotor and is broken up by this as soon as the spinning rotor starts to rotate. For separating and preparing the yarn end, the rim of the spinning rotor features separating structures. To produce the separating structures, the rim of the spinning rotor is provided with cuts, which provide the effect of a saw. According to an alternative embodiment, the cuts are filled with an abrasive material, which then also has a sawing or grinding action.
DE 10 2015 117 204 A1 likewise shows such a spinning rotor with separating structures for preparing a yarn end for piecing. In doing so, the separating structures are not formed by cutting, but by knurling on the spinning rotor.